1. Field of the Invention
The present invention relates to a transmission apparatus and a transmission method for wirelessly transmitting image data.
2. Description of the Related Art
In a system that wirelessly transmits compression-coded image data, a transmission apparatus controls a transmission rate based on a communication quality that changes with time due to a change in a communication environment. In other words, the transmission apparatus raises the transmission rate when the communication quality is high and lowers the transmission rate when the communication quality is low. As a method of detecting a communication quality that changes due to a change in the communication environment, there is a method of detecting a communication state based on an electric field intensity of reception radio waves, an error rate, and a retransmission request count that is based on an error rate (see, for example, Japanese Patent Application Laid-open No. 2004-343726 (paragraph [0009])). In addition, for suppressing a buffer overflow and underflow, the transmission apparatus controls an image transmission rate as a generated code amount of an encoder per unit time together with the transmission rate.
For example, Japanese Patent Application Laid-open No. 2007-194706 (paragraph [0005])) discloses a wireless communication system that performs communication by varying a compression rate of video and image data based on a radio wave propagation environment in which an error may be caused by multipath, changing a symbol rate (clock frequency) along therewith, and setting a propagation path difference due to multipath to fall within a range in which it does not become an error.